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Why oceanic crust is always subducted underneath continental crust?
Oceanic crust is denser than continental crust, so when they collide, the denser oceanic crust is forced beneath the lighter continental crust in a process known as subduction. This subduction occurs at convergent plate boundaries where two plates are moving towards each other. The sinking oceanic crust can trigger volcanic activity and create mountain ranges on the continental crust.
What is a continental arc?
Is a tectonic process where two plates ( an Oceanic plate and a Continental plate) collide. In Continental Arc environments the weaker oceanic plate always sub ducts under the stronger Continental plate. Most Continental arc environments lead to Volcano formation.
These are formed when oceanic plates slide under continental plates?
Subduction zones are formed when oceanic plates slide beneath continental plates. The process leads to the oceanic plate being forced into the Earth's mantle. This can result in the formation of deep oceanic trenches and volcanic activity at the surface.
Are rocks on the seafloor older then the continental rocks?
No. Continental rocks are much older. New sea floor is constantly being create and destroyed. At mid-ocean ridges, the sea floor spreads and magma from deeper in the Earth pushes up to create new ocean crust. At places where ocean plates contact continental plates, the ocean plate is often pushed underneath the continental plate, in a process called subduction. As the ocean plate is pushed back down into the Earth, the heat and the pressure melt it down, destroying it. Since continental plates are very rarely subducted, and, with the exception of places like Iceland where a mid-ocean ridge actually rises above sea level, generally rocks on the continent will be older.
How is the difference in density between the oceanic crust and the continental crust important?
Oceanic crust is thin, dense and composed of mainly silicon and magnessium While the Continental crust is thicker but less dense in comparism with the oceanic crust and its composed mainly of silicon and aluminium.
Why oceanic crust is always subducted underneath continental crust?
Oceanic crust is denser than continental crust, so when they collide, the denser oceanic crust is forced beneath the lighter continental crust in a process known as subduction. This subduction occurs at convergent plate boundaries where two plates are moving towards each other. The sinking oceanic crust can trigger volcanic activity and create mountain ranges on the continental crust.
Why is an oceanic plate always subducted but not a continental plate?
Continental plates are lighter (less dense) than oceanic plates.
When an oceanic plate collides with a continental plate which plate is subducted?
When an oceanic plate and a continental plate collide, the oceanic plate is always subducted. Oceanic plates are denser than continental plates, and they have a higher iron content. Since they are denser, oceanic plates always sink below the continental plate in the event of a collision.
Do the continental plates remain in one place?
No, both the continental and oceanic plates are always moving. Moving slowly, but always moving.
Why does oceanic rock always sink below continental rock?
subduction
Why are continental plates are made up of older rocks?
Continental Plates are made of old rocks because they are never created or destroyed. For example, when an earthquake occurs, it can be caused by one tectonic plate going underneath another. The plate that goes underneath is always an oceanic plate because the rock is of a higher density. So, in summary, continental plates are lighter than oceanic crust, so they are never destroyed (hence why they are made of old rock).
What is likely to occur at a plate boundary where the oceanic crust collides with the continental crust?
The oceanic plate is made of denser (and thinner) rock than the continental crust, so the oceanic plate gets subducted (pushed underneath) where it descends and gets melted by geothermal heat.
What is a continental arc?
Is a tectonic process where two plates ( an Oceanic plate and a Continental plate) collide. In Continental Arc environments the weaker oceanic plate always sub ducts under the stronger Continental plate. Most Continental arc environments lead to Volcano formation.
Why is oceanic plate denser than continental plate?
Oceanic plates are primarily made up of basaltic rock while continental plates are primarily made of granitic rock. Basalt is denser than granite which allows oceanic plates to subduct beneath continental plates.
How does subduction effect Volcanoes?
Subduction zones involve an oceanic plate sliding beneath either a continental plateor another oceanic plate (that is, the subducted plate is always oceanic while the subducting plate may or may not be oceanic). Subduction zones are often noted for their high rates of volcanism, earthquakes, and mountain building. This is because subduction processes result in melt of the mantle that produces a volcanic arc as relatively lighter rock is forcibly submerged.
Can continental lithosphere subduct?
Not usually, as the rock they are made of (mostly granite) is too light to sink into the mantle (mostly denser basalt). Small fragments of continental crust can get entrained in a subducting oceanic plate and be dragged down into the mantle as that plate subducts. Where continental crust collides with oceanic crust, it always floats forcing the oceanic crust down and causing it to subduct. Where continental crust collides with continental crust, both plates crumple and compress dramatically, being forced upward into unusually high mountains (e.g. the Himalayas) and downward into deep continental roots that support the weight of those mountains. Nothing subducts in this case. But whole continental plates subducting does not happen, while much more oceanic plate area has been subducted in the history of the earth than the total surface area of the earth.
What is the difference between contiental crust and oceanic crust?
Continental crust is on top of the oceanic crust Continental crust is made of granite whereas oceanic crust is made of basalt Continental crust is partly above sea level and partly below whereas oceanic crust is always below sea level.
